Organic sulfenyl thiocyanates



Patented Oct. 23, 1951 ORGANIC SULFENYL THIOCYANATES Chester M. Himel,Palo Alto, Calif., and Lee 0.

Edmonds, Bartlesville, kla.,

assignors to Phillips Petroleum Company, a corporation of Delaware NoDrawing. Application December 12, 1949, Serial No. 132,628

13 Claims.

This invention relates to a process for the preparation of an organicsulfenyl thiocyanate. In one embodiment of the invention it relates tothe preparation of an alkyl sulfenyl thiocyanate by interaction betweenan alkyl thiosulfenyl halide and an inorganic metal cyanide. The processof the invention can be effected by bringing together a thiosulfenylhalide and a metal cyanide, or by admixing a solution of a thiosulfenylhalide in an organic solvent and an aqueous metal hydroxide solution andadding hydrogen cyanide to the resulting mixture.

The organic sulfenyl thiocyanate products of the present invention areuseful for various com mercial purposes. Thus, they may be used aspest-control agents, e. g., insecticides, bactericides, fungicides, andas intermediates in the preparation of other chemical compounds.

A method of the prior art as reported in the literature involves thereaction of a mercaptan with thiocyanogen. This process is not entirelysatisfactory because of the loss of reactants and the difficulty ofrecovery since an excess of thiocyanogen is required to obtain desirableyields of the sulfenyl thiocyanate and in the recovery of the productthe excess of thiocyanogen and thiocyanic acid by-product must bedecomposed in order to permit the isolation of the desired product. Inour copending application, Serial No.

66,584, filed December 21, 1948, another method,

particularly adaptable for the preparation of the tertiary alkylderivatives, is described for the production of sulfenyl thiocyanatesfrom the interaction of corresponding alkyl sulfenyl halides withselected metal salts of thiocyanic acid.

We have now found that organic sulfenyl thiocyanates can be readilyprepared and recovered by the interaction of organic thiosulfenyl halieswith a metal cyanide. In a preferred manner of preparation, the organicthiosulfenyl halide is dissolved in an organic solvent, preferably alow-boiling hydrocarbon, and to this solution is added a selected metalcyanide which may conveniently be added as an aqueous solution thereof.The solvent is flashed off and the product is easily recovered byfractionation, preferably at reduced pressures. In a modification of theprocess a mixture of an organic soution of the thiosulfenyl halide andaqueous metal 2 hydroxide solution may be contacted with hydrogencyanide under the conditions described below to effect the formation ofthe sulfenyl thiocyanate.

The reaction, according to this invention, may be represented asfollows:

where R represents an alkyl, aralkyl, or aryl group; X is a halogen fromthe group consisting of chlorine, bromine, and iodine; and M representsan a kali or alkaline earth metal.

The reaction of this invention can be effected employed in themodification described. For sim- I plicity of operation and from acommercial viewpoint, the use of the aqueous solution of alkali metalhydroxide and hydrogen cyanide may have certain economic advantages.

The thiosulfenyl halides which can be used in the process of thisinvention are the thiosulfenyl chlorides, bromides and iodides. Ingeneral, it is preferred to use the chlorides because of their low costof manufacture. Different organic thiosulfenyl halides containing avarying humber of carbon atoms and of varying carbon configuration maybe employed in the present process, which is, however, particularlyadaptable to preparation of alkyl sulfenyl thiocyanates in which thealkyl group contains at least one carbon atom and as many as twelvecarbon atoms. Thus the alkyl thiosulfenyl halides can be methyl, ethyl,propyl, isopropyl, butyl, isobutyl, etc, thiosulfenyl halide up to andincluding dodecyl thiosulfenyl halide. Especially good results have beenobtained when the alkyl group is of the tertiary configuration and hasbetween 4 and 12 carbon atoms. Of this group of alkyl thiosulfenylhalides, the tertiary butyl, tertiary pentyl, tertiary hexyl, etc. up toand including the tertiary dodecyl thiosufenyl halides are illustrative.

It is particularly efficacious to employ a solvent in the preparation ofthe thiosulfenyl halides which is also satisfactory in the presentprocess in which the thiosulfenyl halide is preferably dissolved in anorganic solution when admixed with an aqueous solution of the cyanidereactant.

The solvent used for the reaction medium and in which the halides may beinitially prepared and dissolved is preferably a low-boiling hydrocarbonor mixture of paraffinic hydrocarbons such as pentanes, hexanes, andheptanes. However, other inert organic solvents, such as diethyl ether,chloroform and other low boiling organic solvents, which are inert withrespect to both reactants and product, may be employed. The thiosulfenylhalide is preferably present in the solvent in a concentration between 5and 40 per cent.

The metal cyanides used will preferably be those of the alkali metals,although the cyanides of the alkaline earth metals may be used whendesirable. The cyanide salt of any of the various alkali metals may beused but it is generally preferred to employ sodium salt because of itscheapness and ready availability. The metal cyanide is introduced as asolution in water, usually in a concentration of from 5 to 50 per cent,preferably from 10 to 30 per cent.

The preparation of the sulfenyl thiocyanates can be efiected by bringingtogether the reactants at a temperature within the range of about l C.to about 50 C. Temperatures without this range do not appear to add anyspecial advantage; however, it will be understood the temperaturesemployed may extend above or below this range if desired. The preferredtemperatures will be between and 30 C., more particularly between 15 and25 C. It is particularly effective to employ as the solvent a lowboilinghydrocarbon such as p'entane and to carry out the reaction at theboiling temperature of the solvent and in the presence of refluxingsolvent. By operating in this manner, a constant temperature level ismaintained and a certain degree of the agitation of the system isautomatically provided.

The time for the reaction to be completed will depend upon theparticular thiosulfenyl halide and the temperature employed, as well asupon other conditions which may exist, such as the total quantity ofreactants present and the solvent employed. Ordinarily, with quantitiesof the reactants, as shown in the example below,

a time of about minutes to about 90 minutes i will be sufiicient tosubstantially complete the reaction after the addition of the metalcyanide or hydrogen cyanide has been accomplished.

The reaction of this invention appears to be substantially independentof the pressure and there appears to be no special advantage in the useof pressures other than the prevailing atmospheric. However, thepressure employed should be at least that required to maintain reactantsin a liquid phase at the operating temperature.

As above stated, the thiosulfenyl halide is admixed with an aqueoussolution of the metal cyanide in a niol to mol ratio of substantially1:1, although a small excess of the cyanide, generally not more than molper cent, can be used when desired. Usually, the thiosulfenyl halidesform a colored organic solution while the resulting sulfenylthiocyanates are clear. In these cases it can be readily observed whenreaction is substantially complete, although it is advisable to continueoperation for a short time after the coloration has apparentlydisappeared.

The following example illustrates a particular application of theinvention and conditions under 4 which a specific alkyl sulfenylthiocyanate is prepared.

Example A reactor was charged with 49 grams of sodium cyanide in 20 percent aqueous solution and 156 grams of tertiary-butyl thiosulfenylchloride in 1600 ml. of isopentane. The mixture was maintained at thetemperature of boiling isopentane (28 C.) until the color was discharged(about 30 minutes). The mixture was stirred for an additional 30 minutesafter which the organic layer was separated from the aqueous phase. Theisopentane was flashed off after which the product was distilled underreduced pressure to provide a yield of 133 grams of tertiary-butylsulfenyl thiocyanate boiling at 65-70 C. under a pressure of 10 mm. andhaving an index of refraction n 1.5080.

The nature and advantages of the present invention will be clear fromthe foregoin disclosure and example which is illustrative only and notintended to unduly limit the inherent scope of the invention.

We claim:

1. A process for the preparation of an organic sulfenyl thiocyanatewhich comprises reacting a thiosulfenyl halide selected from the groupconsisting of thiosulfenyl chlorides, bromides and iodides with a metalsalt of hydrocyanic acid.

2. A process according to claim 1 in which said thiosulfenyl halide is athiosulfenyl chloride.

3. A process for the preparation of an organic sulfenyl thiocyanatewhich comprises admixing a thiosulfenyl halide selected from the groupconsisting of thio'sulfenyl chlorides, bromides and iodides with a metalcyanide in the presence of an organic solvent for a time sufficient toform said sulfenyl thiocyanate.

4. A process for the preparation of an. alkyl sulfenyl thiocyanate whichcomprises admixing an alkyl thiosulfenyl halide selected from the groupconsisting of alkyl thiosulfenyl chlorides, bromides and iodides in thepresence of an organic solvent with an aqueous solution of a metalcyanide for a sufficient time to form said alkyl sulfenyl thiocyanate.

5. A process for the preparation of a sulfenyl thiocyanate whichcomprises admixing a thiosulfenyl halide selected from the group consisting of thiosulfenyl chlorides, bromides and iodides and a metalcyanide at a temperature between l0 C. and 50 C. in the presence of alow-boiling hydrocarbon solvent for a time sufficient to form saidsulfenyl thiocyanate.

6. A process according to claim 5 in which said halide is a thiosulfenylchloride.

'7. A process according to claim 5 in which said metal cyanide is analkali metal cyanide.

8. A process according to claim 5 in which said metal cyanide is sodiumcyanide.

9. A process for the preparation of an alkyl sulfenyl thiocyanate whichcomprises contacting an alkyl thiosulfenyl halide selected from thegroup consisting of alkyl thiosulfenyl chlorides, bromides and iodidesdissolved in an inert organic solvent with an aqueous solution of ametal cyanide at a temperature between -10" C. and

10. A process according to claim 9 in which said alkyl thiosulfenylhalide has an alkyl radical containing between one and twelve carbonatoms.

11. A process according to claim 9 wherein said alkyl thiosulfenylhalide has a tertiary alkyl radical.

12. A process according to claim 9 wherein said alkyl thiosulfenylhalide is selected from the group comprised consisting of thiosulfenylchlorides, bromides and iodides having a tertiary alkyl radicalcontaining from four to twelve car bon atoms.

13. A process for the preparation of tertiarybutyl sulfenyl thiocyanatewhich comprises reacting tertiary-butyl thiosulfenyl chloride in anexcess of isopentane with an aqueous solution of sodium cyanide at atemperature of about 28 C. for a time sufficient to form said butylsulfenyl-thiocyanate.

CHESTER M. HIMEL. LEE 0. EDMONDS.

REFERENCES CITED UNITED STATES PATENTS Name Date Schulze July 5, 1938OTHER REFERENCES Zincke et al.: Berichte, v01. 51, pp. 751-767 (1918).

Number

1. A PROCESS FOR THE PREPARATION OF AN ORGANIC SULFENYL THIOCYANATEWHICH COMPRISES REACTING A THIOSULFENYL HALIDE SELECTED FROM THE GROUPCONSISTING OF THIOSULFENYL CHLORIDES, BROMIDES AND IODIDES WITH A METALSALT OF HYDROCYANIC ACID.